1. Field of the Invention
The present invention relates to a method and an arrangement for rolling hot wide strips from continuously cast thin slabs in successive steps of operation of a rolling line which includes a continuous finishing train. The method includes producing continuously cast strands in one or more casting machines or casting lines and severing individual thin slabs from the cast strand and homogenizing and adjusting to rolling temperature the thin slabs in an equalizing furnace provided in each casting line and transferring the slabs from the equalizing furnace to the rolling line.
2. Description of the Related Art
The following types of arrangements are known for two-strand and three-strand plants:
The thin slabs, arriving from different continuous casting machines, initially travel through an equalizing furnace, and are subsequently subjected to a breaking-down treatment and are then wound into coils. The coils are transported by means of various conveying means in the covered slate to the center line of the CSP rolling mill train (CSP compact strip production) and, after uncoiling, for example, in a coil box, are conveyed to the rolling mill train.
In order to have available more buffer possibilities, German Offenlegungsschrift 38 21 188.2 discloses an intermediately arranged rotary hearth furnace, which is capable of keeping the wound coils hot. The known method and the corresponding arrangement provide that the initial material is adjusted to hot-rolling temperature after solidification and is wound into coils, is intermediately stored in a rotary hearth furnace and is called up as desired, and is uncoiled and rolled into finished strips. It is particularly advantageous if the intermediate storage occurs immediately before the entry into the finishing train. Afterheating can be carried out during the intermediate storage.
In accordance with another type of arrangement, one or two transversely movable furnace conveyors are arranged at the ends of the equalizing furnaces, which extend parallel to each other and are arranged following each continuous casting machine. The furnace conveyors move the thin slabs into the region of the rolling mill train or the rolling line.
Finally, another known type of arrangement provides that two or three continuous casting machines or casting lines are arranged offset and at an angle relative to each other. The equalizing furnaces are also arranged in an angularly offset configuration in the casting lines. A roller conveyor is provided at the ends of the equalizing furnaces. The roller conveyor receives the thin slabs from the furnaces and swings the thin slabs in the manner of a turntable into the rolling line and feeds them to the rolling mill in this manner.
The known types of arrangements start, in part, from the same objects which are, inter alia, the requirements to reduce as much as possible the temperature losses of the continuously cast initial material on the way into the rolling mill and, for this purpose, in addition to providing suitable heat-insulating features, to maintain short conveying distances and conveying periods. In addition, it is another object to harmonize the casting capacities of several casting machines and the rolling capacity of a subsequent rolling mill in such a way that the entire plant is utilized with as few losses as possible in order to achieve an economically favorable operation. Also, the space required by the plants and, thus, the investment costs should be minimized.
In order to convey continuously cast thin slabs of different casting lines without problems and quickly into a rolling line, it is always necessary to provide special additional conveying units in the arrangement. Required for this purpose are, for example, transverse conveying units and/or displacement units or also coiling units which are not only structurally very complicated, but also require substantial space because the thin slabs are up to 60 m long. As a consequence, the investment costs and operation costs are very high.